The subject matter disclosed herein relates to pressure controller system valves and particularly to characterizing pressure controller system valves.
Pressure controller systems are devices for manipulating the pressure of gases. These devices can be used in a variety of fields, such as aeronautics, industrial, scientific, manufacturing, and automobile environments. For example, pressure controller systems are used in air data test sets (ADTS), compressor control and monitoring, automotive engine development, turbine monitoring and control, and flight tests, among others.
A pressure controller system includes an apply valve and a release valve. The pressure controller system can control pressure by driving the valve plungers up and down using electronic solenoid currents. If the pressure in the controller manifold is greater than a set-point, the controller closes the apply valve an amount and opens the release valve an amount, so that the mass flowrate of the gas flowing into the manifold is less than that out of the manifold. The pressure thus decreases towards the set-point. If the pressure in the manifold is less than the set-point, the controller opens the apply valve an amount and closes the release valve an amount, increasing the manifold pressure towards the set-point. The electronic solenoid current which drives the apply valve and the release valve is a function of pressure, mass flowrate, and temperature, and the process of knowing this relationship is called valve characterization.
Controller apply and release valves are the only dynamic components of the pressure controller system. The remaining controller components are static components. Thus, valve characterization is important to the accuracy and precision of a pressure controller system. Typically, a valve is characterized by static, point-to-point of pressure measurements. Because a small internal volume of a manifold can be quickly filled by a gas, even by a small mass flowrate, an external auxiliary pneumatic tank is employed to test the entire range of solenoid current, mass flowrate and pressure ranges, point by point.
This traditional valve characterization method is slow, taking at least forty minutes for a single process of typically sixteen points, if the process is successful. If the process fails, the process is repeated a second or third time. If the process still fails, the valve pair is discarded, a new pair of valves is installed, and the characterization process begins again. Thus, traditional valve characterization is a lengthy process, even with a successful pass on the first attempt. In addition, customers do not have the facility to perform tradition characterization. Rather, traditional characterization is performed in a factory for a new instrument or when a valve requires replacement after service. In addition, traditional characterization is unsuitable for low temperatures. At low temperatures, a valve plunger freezes and sticks to its seat. Because of this sticking, a large solenoid current is required to lift the plunger from its seat at low temperature. Once the plunger is lifted, the plunger jumps too much, leading to a pressure glitch. Because of this limitation, traditional valve characterization is not suitable for use in low temperature environments, thus limiting potential environment applications of pressure valve characterization.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.